Manchester United's players turned against each other in the dressing room after their 3-1 defeat to Brighton on Saturday, according to reports.
Erik ten Hag's side sunk to their third loss of the new Premier League season as they were outclassed by Roberto De Zerbi's men at Old Trafford.
The defeat has left United with just six points from their opening five games, while they already trail Premier League champions and current leaders Manchester City by nine points.
According to The Sun, tempers flared between the United players after they were beaten by Brighton as Ten Hag 'attempted to restore order' among his squad.
The report claims that United captain Bruno Fernandes 'confronted' Scott McTominay, who had been given his first start of the season.
Lisandro Martinez, who was sold a dummy by Pascal Gross for Brighton's well-worked second goal, was also said to have 'lost it' with his centre-back partner Victor Lindelof in the dressing room.
United now turn their attention to the Champions League following their year-long absence from the competition.
Ten Hag's side begin their campaign on Wednesday with their toughest fixture in Group A - a trip to Bayern Munich.
But despite United's rocky start to the new Premier League season, Bayern Munich's £100 million summer signing Harry Kane insists Ten Hag's side will be a tricky opponent.
'It's going to be a tough game, first and foremost,' Kane told CBS.
'They're in a little bit of a tricky patch at the moment but sometimes they're the most dangerous team to play against.
'They're always looking to fight back and get a big result, so we're just focused on playing against a really good team.'